An exemplary lens module includes a barrel, a holder receiving the barrel therein, and lenses received in the barrel. The barrel includes a circular peripheral barrel wall. An inner diameter and an outer diameter of the barrel both gradually increase from an object side to an imaging side. The holder includes a peripheral holder wall. An inner diameter of the holder gradually increases from the object side to the imaging side. The peripheral barrel wall is engaged with the peripheral holder wall. Diameters of the lenses gradually increase from the object side to the imaging side.